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Jay Saunders picked up a point in his first game in charge of Margate on Saturday.
Tonbridge looked like continuing their winning run at a windswept Longmead thanks to Joe Turner's first-half penalty.
But Ben Swift headed in from close range with just seven minutes left to hand Gate a vital Bostik Premier point.
Tonbridge started brightly, full-back James Folkes shooting narrowly wide from the edge of the box inside four minutes.
The breakthrough arrived on 25 minutes after a period of pressure. Chinedu McKenzie's deflected near post effort was turned behind by keeper Louis Wells.
The resulting corner was sliced behind for another set-piece, from which Swift inexplicably handled the ball under pressure from Arthur Lee.
Referee Lee Dyson pointed to the spot and, after cautioning Swift, Turner fired home the penalty.
Margate looked to the width of loan signing Kadell Daniel and Joseph Hungbo.
The latter cut inside before seeing his low shot kept out by keeper Jon Henly, then the former fed Alex Flisher whose shot lacked power.
Gate replaced the ineffective Bradley Stevenson with Dave Martin at the break, switching to 4-4-2 and moving Daniel up front alongside Flisher.
Skipper Liam Friend headed over a corner but at the other end Tonbridge had two good openings, Connor Dymond heading off his own line before McKenzie's low effort went just wide of the upright.
The introduction of Sid Sollis saw Gate play with three up front but Tonbridge's defence held firm, with Sonny Miles and Arthur Lee particularly impressive.
Martin went close to finding an equaliser with 20 minutes left but his header from Dymond's cross was straight at Henly.
Martin certainly was in the game, escaping with just a yellow card 11 minutes from time for a needless lunge at keeper Henly.
The equaliser finally arrived for the visitors with seven minutes remaining. Martin's corner from the left was met at close range by Swift, who headed in beyond Henly.
Gate's Jordan Robins was then booked for a cynical foul on Turner, who escaped any punishment after pushing away the offender.
Tonbridge: Henly, Folkes, Parter, Theobalds, Miles, Lee, Ramaden, Beere, Read (Small 82mins), McKenzie, Turner. Subs not used: Smith, Lewis, Stirman.
Margate: Wells, Dymond, Mills, Rogers, Friend, Swift, Daniel, Robins, Flisher, Stevenson (Martin 46mins), Hungbo (Sollis 64mins). Subs not used: Kallmeier, Barnard, Paxman.
Attendance: 530.